Described below is a method for transmitting messages between control units of a motor vehicle. The messages are transmitted as data packets via a data network in which at least one switch apparatus (switch) forwards or assigns the messages.
In a motor vehicle, a requirement is usually imposed on the data network with respect to the temporal behavior in order to limit a maximum transmission period for certain messages, for example from a safety-relevant driver assistance system. Time-controlled approaches in the form of data buses, such as FlexRay or the TTEthernet or TTP, are known for this purpose. These are based on a time-controlled transmission plan or schedule which must be implemented in all control units involved. However, this results in the entire data network being based on a global static schedule which requires an adaptation for all control units if a new control unit is intended to be retrofitted.
DE 103 09 164 A1 discloses a method for providing a schedule in a so-called switched network. Data messages to be transmitted in real time are transmitted separately from other data messages. However, this means that the real-time data messages must wait during the transmission of the other data messages.
DE 10 2011 076 357 A1 discloses a data network for an aircraft, in which data are provided with priorities in order to hereby give preference to the forwarding of particularly important data. However, this cannot prevent a control unit having a multiplicity of unimportant data packets from still being able to hinder the data traffic in the network.
DE 10 2007 061 986 A1 discloses a method for also being able to provide packet-based data traffic in a time-controlled bus system, for example the FlexRay bus.
WO 2010/136023 A1 discloses a method for optimizing packet-based data transmission. Data packets are here provided with a priority in order to be able to transmit them in the order of their importance in the local Ethernet network. Data packets having a high priority can be passed via their own queue.